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Ag2S-Glutathione Quantum Dots for NIR Image Guided Photothermal Therapy
摘要： Aqueous synthesis of glutathione (GSH) coated Ag2S quantum dots (QD) with strong emission in the medical imaging window (700-900 nm) were prepared from AgNO3. Variations in temperature, time, pH and sulfur source (Na2S and thioacetamide) were studied to tune the emission wavelength and intensity of QDs. The optimum synthesis condition to produce the smallest QDs (ca 7 nm) with the highest quantum yield (70 %) and excellent stability was determined as 50 ℃ and pH 10 where Na2S was used in 2 h reactions. Cytotoxicity was evaluated with MTT assay on HT29 and MCF7 cancer cell lines and indicated no significant toxicity of QDs up to 200 μg/mL. Photothermal Therapy (PTT) potential was first investigated by 795 nm, continuous-wave fiber coupled diode laser using aqueous solutions of QDs and then on HT29 and MCF7 cells. QD (150 μg/mL) treated MCF7 cells almost quantitatively died after 10 min irradiation at 795 nm (700 mW, 1.82 W/cm2) and the viability of HT29 cells dropped to 40%. Most cell death was late apoptotic/necrotic. This study indicates that such laser irradiation procedure and the QDs are safe yet, their combination provides a dramatic cell death upon short laser treatment. PTT coupled with strong intracellular optical signal promotes Ag2S-GSH QDs as potential theranostic nanoparticles.
关键词： glutathione coating,NIR imaging,Ag2S quantum dots,theranostic nanoparticles,photothermal therapy
更新于2025-09-23 15:19:57
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Thioglycolic Acid FTIR Spectra on Ag2S Quantum Dots Interfaces
摘要： The mechanism features of colloidal quantum dots (QDs) passivation with thioglycolic acid molecules (TGA) for cases of different luminescent properties is considered using FTIR. This problem is considered based on FTIR spectra analysis for various ionic forms of TGA. Experimental TGA molecules FTIR spectra is interpreted, basing on the data on modeling of TGA vibrational modes, realized in the framework of density functional method (DFT /B3LYP/6-31+G(d)) taking into account the vibrations anharmonicity of every functional group. This approach provides a significant improvement in the agreement between the experimental and calculated data. FTIR spectra of Ag2S/TGA QDs with exciton and recombination luminescence are differ from each other and B “freeB” TGA molecules. The ν(S ? H) TGA peak (2559 cm?1) disappears in FTIR spectra of Ag2S/TGA QD samples. This fact indicates the interactions between TGA thiol group and dangling bonds of Ag2S nanocrystals. Ag2S QDs passivation with TGA molecules leads to emergence νas(COO?) (1584 cm?1) and νs(COO?) (1387 cm?1) peaks. It indicates TGA adsorption in ionic form. For Ag2S/TGA QDs with exciton luminescence we observed (a) significant low-frequency shift of νs(COO?) peak from 1388 cm?1 to 1359 cm?1 and high-frequency shift of νas(COO?) peak from 1567 cm?1 to 1581 cm?1; (b) change in the ratio of intensities of νas(COO?) and νs(COO?) vibrations. This feature is caused by the change in the symmetry of TGA molecules due to passivation of Ag2S quantum dots.For Ag2S/TGA QDs with recombination luminescence, the insignificant high-frequency shift of 7–10 cm?1 for νas (COO?) at 1567 cm?1 and low-frequency shift of 3–5 cm?1 for νs (COO?) at 1388 cm?1, probably caused by the interaction of thiol with Ag2S surface is observed. Using FTIR spectra, it was found that IR luminescence photodegradation is also accompanied by changes in the thioglycolic acid molecules, which capped Ag2S QDs. In the case of Ag2S QDs with exciton luminescence, the degradation process is non-reversible. It is accompanied by TGA photodegradation with the formation of α-thiol-substituted acyl radical (S-CH2-CO?) TGA.
关键词： photodegradation,FTIR spectra,thioglycolic acid (TGA),dimer,luminescence,Ag2S quantum dots,ionic form
更新于2025-09-23 15:19:57
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Spectroscopic and Electrical Properties of Ag2S/PVA Nanocomposite Films for Visible-Light Optoelectronic Devices
摘要： Polymer nanocomposites are potential materials in the industrial sector and in our daily life due to their diverse properties and applications. Throughout the present study, solution casting technique has been used to prepare polyvinyl alcohol (PVA) filled with different weight (wt.) ratios percentages (%) (0, 0.01, 0.1, 1.0 and 10.0 wt%) of silver sulfide nanoparticles (Ag2S NPs). The concentration dependence of spectroscopic and electrical behaviors based on PVA polymer dispersed with Ag2S has been investigated. The prepared films with the variation of loading filler concentrations from 0 to 10 wt% have been characterized by different spectroscopic techniques. Fourier transform infrared (FTIR) analysis confirmed the successful incorporation of Ag2S nanoparticles in the PVA matrix by studying the changes of the characterizing bands which reveal the interaction within the composite structure. Whilst photoluminescence (PL) spectra of the Ag2S/PVA nanocomposite films showed an interesting peak covering the entire range of interest for visible light optoelectronic devices at a very low concentration of the loading filler of Ag2S. The electrical properties of the plain and Ag2S NPs doped PVA nanocomposites have been studied using DC electrical conductivity (σDC) measurements performed over a temperature (T) range from 298 to 373 K. The study demonstrates the increase of the DC electrical conductivity with increasing filler content of Ag2S by three orders of magnitude. DC conductivity also showed temperature dependent behavior where the conductivity enhanced by five orders of magnitude when temperature increased up to 373 K. These novel results present Ag2S/PVA nanocomposites as a promising material in optoelectronics applications.
关键词： DC conductivity,FTIR spectroscopy,Ag2S,PVA nanocomposites,Photoluminescence,Optoelectronic devices
更新于2025-09-23 15:19:57
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Infrared fluorescence imaging of infarcted hearts with Ag2S nanodots
摘要： Ag2S nanodots have already been demonstrated as promising near-infrared (NIR-II, 1.0–1.45 μm) emitting nanoprobes with low toxicity, high penetration and high resolution for in vivo imaging of, for example, tumors and vasculature. In this work, we have systematically investigated the potential application of functionalized Ag2S nanodots for accurate imaging of damaged myocardium tissues after a myocardial infarction induced by either partial or global ischemia. Ag2S nanodots surface-functionalized with the angiotensin II peptide (ATII) have shown over 10-fold enhanced binding efficiency to damaged tissues than non-specifically (PEG) functionalized Ag2S nanodots due to their interaction with the upregulated angiotensin II receptor type I (AT1R). It is demonstrated how the NIR-II images generated by ATII-functionalized Ag2S nanodots contain valuable information about the location and extension of damaged tissue in the myocardium allowing for a proper identification of the occluded artery as well as an indirect evaluation of the damage level. The potential application of Ag2S nanodots in the near future for in vivo imaging of myocardial infarction was also corroborated by performing proof of concept whole body imaging experiments.
关键词： Ag2S,biological windows,infrared imaging,Langendorff heart,myocardial infarct,nanodots
更新于2025-09-19 17:15:36
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Controlled growth of Cu <sub/>2a??x</sub> S sheet-like nanoshells and Cu <sub/>2a??x</sub> Sa??CdS pa??n junctions on Au nanorods with coupled plasmon resonances and enhanced photocatalytic activities
摘要： In this study, we propose an approach to grow Cu2?xS sheet-like nanoshells on Au nanorods with the aid of Ag2S auxiliary templates. The Ag2S semi-shells are first grown on the side-surface of the Au nanorods and then, the Cu2?xS sheet-like nanoshells are selectively grown on the opposite side, which is beneficial for improving the controllability of the growth sites of the Cu2?xS sheet-like nanoshells. The Cu2?xS–CdS p–n junctions grown on Au nanorods are produced by replacing Ag+ with Cd2+ in the as-prepared Au/(Cu2?xS–Ag2S), so that Au/(Cu2?xS–CdS) heterorods with non-central symmetric shells of Cu2?xS–CdS p–n junctions are formed. By carefully adjusting the effective thickness of the Cu2?xS–CdS junctions, the optimized photocatalytic activity of the Au/(Cu2?xS–CdS) heterorods is obtained, and it is about 1.62 and 1.22-fold that of Au/Cu2?xS and Au/CdS, respectively. The improved photocatalytic performance of the Au/(Cu2?xS–CdS) heterorods is attributed to the effective charge carriers at the interfaces of CdS–Au, Cu2?xS–Au and the Cu2?xS–CdS p–n junction. Our findings provide a strategy for the optimal design of plasmon–exciton heterostructures with improved photocatalytic activity.
关键词： Cu2?xS,Ag2S auxiliary templates,plasmon resonances,photocatalytic activities,Au nanorods
更新于2025-09-19 17:13:59
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A solid-state integrated photo-supercapacitor based on ZnO nanorod arrays decorated with Ag <sub/>2</sub> S quantum dots as the photoanode and a PEDOT charge storage counter-electrode
摘要： A planar solid-state photocapacitor with two electrodes has been prepared for the first time using a passivated film of ZnS with Ag2S quantum dots deposited on ZnO nanorods, which were electrochemically grown on ZnO seed layers, as the photoanode. The supercapacitor part is composed of a electrodeposited poly(3,4-ethylene-dioxythiophene) PEDOT film as the counter-electrode and an ionic liquid-based electrolyte between them deposited by the dip coating method. The different nanostructures and electrodes were morphologically and structurally characterized, and the device was electrochemically characterized and could reach a potential of 0.33 V during photocharge and a storage efficiency of 6.83%.
关键词： solid-state,ZnO nanorod arrays,electrochemical characterization,PEDOT,photo-supercapacitor,Ag2S quantum dots
更新于2025-09-19 17:13:59
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Bypassing pro-survival and resistance mechanisms of autophagy in EGFR-positive lung cancer cells by targeted delivery of 5FU using theranostic Ag <sub/>2</sub> S quantum dots
摘要： Targeted drug delivery systems that combine imaging and therapeutic functions in a single structure have become very popular in nanomedicine. Near-infrared (NIR) emitting Ag2S quantum dots (QDs) are excellent candidates for this task. Here, we have developed PEGylated Ag2S QDs functionalized with Cetuximab (Cet) antibody and loaded with an anticancer drug, 5-fluorouracil (5FU). These theranostic QDs were used for targeted NIR imaging and treatment of lung cancer using low (H1299) and high (A549) Epidermal Growth Factor Receptor (EGFR) overexpressing cell lines. The Cet conjugated QDs effectively and selectively delivered 5FU to A549 cells and provided significantly enhanced cell death associated with apoptosis. Interestingly, while treatment of cells with free 5FU activated autophagy, a cellular mechanism conferring resistance to cell death, these EGFR targeting multimodal QDs significantly overcame drug resistance compared to 5FU treatment alone. The improved therapeutic outcome of 5FU delivered to A549 cells by Cet conjugated Ag2S QDs is suggested as the synergistic outcome of enhanced receptor mediated uptake of nanoparticles, and hence the drug, coupled with suppressed autophagy even in the absence of addition of an autophagy suppressor.
关键词： lung cancer,EGFR,theranostic,Ag2S quantum dots,autophagy,targeted drug delivery,5-fluorouracil
更新于2025-09-16 10:30:52
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Photostimulated control of luminescence quantum yield for colloidal Ag <sub/>2</sub> S/2-MPA quantum dots
摘要： In this paper, we present the results on photoinduced formation of colloidal Ag2S quantum dots with sizes of 1.5–3 nm passivated by 2-mercaptopropionic acid (Ag2S/2-MPA) in the presence of ethylene glycol. The synthetized colloidal Ag2S/2-MPA QDs have NIR recombination luminescence with its maximum near 800 nm. The control of absorption and luminescence properties of the QDs is achieved by photoactivation. It is shown that photoexposure of colloidal solution of Ag2S/2-MPA QDs leads to an increase in the QD size and monodispersity along side with the growth of the luminescence quantum yield from 1% to 7.9%. Enhancement of the luminescence quantum yield is accompanied by an increase in the average luminescence lifetime up to 190 ns, which is due to the blocking of the nonradiative recombination channel with the radiative recombination rate being (3–5.5) × 105 s?1. It is shown that the purification of the Ag2S/2-MPA solution by a dialysis membrane from regenerated cellulose leads to an increase in the sample monodispersity, as well as stops the photoinduced growth of QDs, and also reduces the degradation of their photoluminescence.
关键词： Ag2S quantum dots,NIR luminescence,2-mercaptopropionic acid,luminescence quantum yield,photoactivation
更新于2025-09-16 10:30:52
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Synthesis of Silver Sulfide Quantum Dots Via the Liquid–Liquid Interface Reaction in a Rotating Packed Bed Reactor
摘要： We developed the high-gravity coupled liquid–liquid interface reaction technique on the basis of the rotating packed bed (RPB) reactor for the continuous and ultrafast synthesis of silver sulfide (Ag2S) quantum dots (QDs) with near-infrared (NIR) luminescence. The formation of Ag2S QDs occurs at the interface of microdroplets, and the average size of Ag2S QDs was 4.5 nm with a narrow size distribution. Ag2S QDs can disperse well in various organic solvents and exhibit NIR luminescence with a peak wavelength at 1270 nm under 980-nm laser excitation. The mechanism of the process intensification was revealed by both the computational fluid dynamics simulation and fluorescence imaging, and the mechanism is attributed to the small and uniform droplet formation in the RPB reactor. This study provides a novel approach for the continuous and ultrafast synthesis of NIR Ag2S QDs for potential scale-up.
关键词： Liquid–liquid interface reaction,Rotating packed bed,Ag2S quantum dots,Near-infrared luminescence,Process intensification
更新于2025-09-12 10:27:22
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Fabrication of Ag2S quantum dots sensitized CdSe photoelectrodes and its photoelectric performance
摘要： Well-aligned wheat-like CdSe nanorods array was fabricated by electrodeposition method, which was sensitized with Ag2S quantum dots (QDs) by using successive ionic layer adsorption and reaction (SILAR) method. The combination of five successive layers Ag2S QDs with CdSe shows maximum short-circuit photocurrent density of 36.88 mA/cm2. Compared with TiO2-based photoelectrode, the wheat-like CdSe nanorods array modified with Ag2S QDs exhibit improved photoelectrochemical (PEC) performance. The main reason for the enhancement of PEC is to use narrow band-gap semiconductor CdSe instead of the conventional wide band-gap oxide as the sensitized substrate of Ag2S QDs. In addition, the synthetic nanocomposites are characterized by analytical techniques such as XRD, UV–vis absorption spectroscopy, FESEM, HRTEM, EDX, XPS and EIS. The results indicate that Ag2S QDs are well grown on the surface of CdSe photoelectrodes. Meantime, the PEC performance of CdSe photoelectrodes has also been improved.
关键词： SILAR,Ag2S,CdSe,Thin films,Quantum dots
更新于2025-09-11 14:15:04